Migratory scraper and valve



June 23, 1970 w. F. WARD 3,516,494

MIGRATORY SCRAPER AND VALVE Filed Sent. 23. 1968 INVENTOR WARREN F. WARD mm W ATTORNEYS United States Patent 3,516,494 MIGRATORY SCRAPER AND VALVE Warren F. Ward, 3601 Turtle Creek, Dallas, Tex. 75219 Filed Sept. 23, 1968, Ser. No. 761,762 Int. Cl. E21b 37/02 US. Cl. 166175 13 Claims ABSTRACT OF THE DISCLOSURE A paraffin scraper which is free to migrate up and down a length of sucker rod to clean the same and also the tubing in which the rod is reciprocating, the scraper having a body surrounding the rod and insertable thereon by way of a slot disposed longitudinally through one side of the body, and the scraper having a sliding valve support and scraping blade assembly extending through the slot and beyond it at each end of the body and supporting a valve member which can either restrict the slot or leave it open depending upon the longitudinal position of the valve assembly with respect to the body, the valve support comprising an actuator having means surrounding the sucker rod above and below the body to guide it thereon and to move the valve into and out of the slot in response to impact against abutments spaced apart along the sucker rod, the longitudinal position of the valve member determining the direction of migration of the scraper on the sucker rod.

This invention relates to self-cleaning oil well paraffin scrapers of the type which surround a sucker rod and migrate up and down substantially the entire length thereof as the well is pumped, and more particularly the invention relates to improvements in parafi'in scraper valve means which operate as a result of contact with spaced abutments on the sucker rod to cause the scraper to rise when it reaches the lower abutment and to fall when it reaches the upper abutment.

It is a principal object of this invention to provide an improved sliding valve assembly for paraflin scrapers capable of migrating up and down a length of sucker rod as it reciprocates in a well for the purpose of cleaning parafiin deposits both from the rod and from the adjacent tubing, the direction of migration of the scraper being determined by said valve assembly which is automaticallyoperated to favor either the effect of gravity or the upward effect of the rising column of fluid on the scraper, in the general way taught by U.S. Pats. 3,330,358 and 3,330,359. These patents show a sliding valve assembly in combination with a body of the type shown in Pats. 2,604,364, 2,793,917 and 3,001,834, which are each characterized by a longitudinal slot through its side wall communicating with a central bore receiving the sucker rod. The present invention provides substantially all of the functions and advantages set forth in detail for the structures disclosed in my US. Pats. 3,330,35 8 and 3,330,- 359, but also provides additional advantages as follows.

It is an important object of this invention to provide an improved sliding valve assembly which is less fragile than the prior art assemblies mentioned above, and which has greater ability to reman in one or another position until it strikes an opposed abutment and reverses its direction. The present structure provides a continuous frictional engagement between the sliding valve assembly and the body portion to provide a drag which is more dependable to hold the valve positioned with respect to the body than the relatively smaller and more localized detents provided in prior art showings. In these prior structures, when the valve was dislodged even slightly from its detent position, there was nothing to prevent it ice from falling open altogether. The present assembly is provided with longitudinal scraper blades which are at all times urged apart to provide frictional drag against the edges of the slot through the body, regardless of the position of the valve assembly with respect to the body.

Another major object of the invention is to provide an improved valve assembly which can also function as a relief valve to bypass any excessive or sudden pressure increases. For instance, a pressure differential of 20 or 30 pounds per square inch on opposite sides of the valve would tend to leave it closed, but a differential pressure of psi. would open it and permit the pressure pocket to pass upwardly through the valve.

Another important object of the invention is to provide a sliding valve assembly in which the sliding motion provides no frictional wear in the valve member itself, the frictional wear being distributed along the relatively large outer surfaces of the blades between which the valve member is located.

A further object of the present invention is to provide a sliding valve assembly which is always precisely centered with respect to the slot regardless of whether the valve member is presently inside the slot or outside. This structure provides a valve which does not hunt as it enters the slot through the body.

Another object of the invention is to provide a valve assembly which can be made of a plastic or of steel, or stainless steel, and in which the valve member itself can then be rubber-coated so as to provide a better sealing action and more corrosion protection. Such rubber coating is made possible by the protective location of the valve member between the two guiding and scraping blades of the assembly.

Still another important advantage of the invention is that the sliding assembly can be made either entirely of one piece of metal or at the most may comprise a relatively simple multiple piece structure which has good strength, and resistance to distortion of sufficient severity to damage the assembly. This assembly, as is the case with the other scraper structures taught in my abovelisted patents, is attachable to a sucker rod anywhere along its length by merely snapping it into the rod, which application requires no alternation of the rod and no tools.

Other objects and advantages will become apparent from a reading of the following discussion of the embodiments shown in the drawing, wherein:

FIG. 1 is a view in perspective showing a valved scraper according to the present invention descending on a sucker rod located within a pump-tubing string, the tubing broken away to show the scraper assembly approaching the upset at the lower end of the illustrated rod;

FIG. 2 is an elevation view of the structure shown in FIG. 1, but showing the scraper after it has contacted the upset and closed valve structure, thereby causing the scraper to rise within the tubing string;

FIG. 3 is an elevation view similar to FIG. 2, but taken at a location near the upper end of the sucker rod and showing the valved scraper assembly abutted against the upper upset of the sucker rod, with the result that the valve member has been moved to an open position, thereby preparing the scraper assembly to commence its descent;

FIG. 4 is an end view of the assembly shown in FIG. 3;

FIG. 5 is a perspective view of a modified form of sliding valve assembly;

FIG. 6 is a perspective view of a further modified Valve member similar in function to the valves shown in FIGS. 1-5, but comprising a rubber or neoprene member; and

FIG. 7 is an elevation view of still a further modified sliding valve assembly of one piece construction, made from a unitary sheet metal stamping.

FIG. 8 is an elevation view partly in cross section showing the present novel scraper applied to a sucker rod between two abutments of the fixed scraper or rod guide type, for instance, such as are shown in my Pat. 2,604,364.

Referring now to the drawings, FIG. 1 shows a sucker rod R disposed within a length of pump tubing T, the latter being shown in cross-section so as to reveal a migratory paraflin scraper assembly according to the present invention located within the tubing. FIGS. 1, 2 and 3 show the paraffin scraper assembly in progressively different positions, as will be described hereinafter. The sucker rod R is a standard rod having an upset U at each end located adjacent wrench flats W which are in turn located near threaded end portions, all of usual design.

The scraper assembly includes a scraper body 1 of a design which is generally well-known in the prior art and is characterized by a substantially cylindrical body having a bore 1a through the center thereof. Since it is necessary that the body slide up and down on the sucker rod, the diameter of the bore 1a is made somewhat greater than the diameter of the sucker rod R between the upsets U. Likewise, the outside diameter of the body '1 is made less than the inside diameter of the tubing T so as to permit the body to freely migrate within the tubing, and the ends of the body are chamfered as at 1b to prevent the body from snagging upon irregularities in the tubing. The body 1 also has a longitudinal slot 10 extend-ing through its side wall, the slot being slightly narrower in width than the diameter of the sucker rod R in the preferred embodiment, whereby the rod can be forced through the slot and entered into the bore 1a with a snapping action. However, the slot 10 really need not be narrower than the rod in order to provide a workable assembly.

The migratory scraper assembly according to the present invention includes, in combination with the abovedescribed scraper body, a sliding valve and scraping assembly for selectively opening or blocking the longitudinal passageway provided by the slot 10 to control the ease with which well fluids can flow therethrough. This valve assembly includes a valve member 2 and a supporting and actuating slide member 3 as shown in detail in FIGS. 1 through 4. The valve member 2 comprises a leaf spring supported at its lower end 2a by a blade member 3b, and urged by its own spring qualities to normally lie against the opposite longitudinal blade member 3a of the slide assembly 3 at its upper end 2b.

The supporting and actuating slide member 3 comprises these two longitudinal blades 3a and 3b joined to two annular strap portions 30 and 3d which are preferably unitary with the blades, probably comprising the same metal stamping. When the slide member 3 is assembled onto the sucker rod, its blades 3a and 3b lie against the opposed surfaces of the slot 10 in the body member 1, and in this position both of the strap portions 30 and 3d loosely surround the sucker rod R without binding thereon. This loose fit is clearly shown in FIG. 1. The lower end 2a of the valve member 2 is secured to the lower end of the blade 3b, for instance by riveting or spot welding, and in this position the valve member lies across the longitudinal passageway between the blades 3a and 3]; so as to effectively close it as shown in FIG. 4.

However, an unusually strong upward surge of hydraulic or gas pressure will displace the upper end 2b of the spring valve member 2 to the left and permit the surge to escape through the passageway P and thereby quickly relieve a surge of unusual severity. Normally, the valve member 2 will remain closed in the presence of a pressure differential in the vicinity of 20 pounds per square inch, but a severe rise in pressure to the level of 100 psi. will cause the valve to be flexed open and thereby quickly relieve the pressure under normal operating conditions. The reference to the valve being open or closed is only relative since the valve can never fully stop the flow of fluid therepast. The escape of some fluid past it at all 4 times provides a desirable jetting action which tends to clean the adjacent parts including the rod R and the tubing T.

One advantage of the present structure is that it can be installed upon a sucker rod without special tools and Without altering or damaging the sucker rod in any way. Installation is achieved by spreading the blades 3a and 3b away from each other to widen the passageway P and thus facilitate insertion of the sucker rod into the openings through the strap portions 3c and 3d. When the slide member 3 is thus installed, the body member 1 is then snapped onto the sucker rod via its slot 10 and in such a position that the scraping and guiding blades 3a and 3b lie against and frictionally drag upon the radially disposed opposite faces of the slot 10. The present invention may include either a rubber body member '1 or a plastic body as alternatively described in above-mentioned Pats. 2,604,364, 2,793,917 and 3,001,834. If a rubber body is used, it is preferably strengthened by inclusion of a C- shaped steel clip K as disclosed in Pats. 2,604,364 and 3,001,834 covering rubber sucker rod guides, and as indicated in dotted lines in FIG. 4. This imbedded steel clip prevents the resilient rubber body from spreading open at slot 10 thereby allowing rod R to leave the central bore 1a of the body '1 and stick in the slot, thereby preventing free travel of the scraper unit along the rod. The rubber body 1 is also provided with narrow pierced radial punctures H extending deeply inwardly to depths short of the embedded steel clip K, said punctures being distributed substantially over all of said body and mutually spaced by distances not exceeding the depths of the punctures as shown in improvement Pat. 3,001,834. These punctures H prevent entrapment of well gases in voids of rubber body by venting same, and also prevent swelling of the body when it is withdrawn from the well to surface atmospheric pressure.

FIG. 5 shows a modified form of slide member and valve assembly, this form being generally referred to by the reference numeral 5 and including blade members 5a and 5b and strap portions 50 and 5a. In over-all appearance this slide member is similar to that shown in FIGS. 1, 2 and 3 except that the outer end-s of the strap portions 50 and 5d have been flared as at 5e and 5 to prevent the ends of the strap portions from gouging the upsets U in the sucker rod R or from binding thereon. Alternatively, fixed-position rubber rod guides can be attached to each end of every supporting sucker rod R to provide shock absorbing abutment means for the strap portions of the slide assembly and serve as rod centralizers in the tubing T to insure free travel of the migratory assemblies. Rubber rod guides are preferable to be used as such abutments to provide a cushioning effect for the migratory assembly. There is novelty in the use of two sizes of normally-fixed rubber rod guides as abutments and migratory scrapers as rod strings in that a x 2" standard guide when mounted on a rod spreads to a greater O.D. than a x 2" guide-scraper body mounted loosely and slideable on a rod, because when unmounted both x 2" and x 2" guides have the same O.D. However, when the /8 x 2 guide is snapped onto a 4; rod, its O.D. increases, whereas a x 2" guide has no spread on a rod. Hence its diameter remains the same. Thus the fixed scraper presents a larger O.D. than the migratory scraper.

The valve members shown in FIGS. 1-5 may comprise one of a number of different materials, including steel perhaps coated with a protective rubber or plastic substance, stainless steel, or even a molded elastic material such as nylon, and in fact, the entire actuating slide member and valve member may be molded of nylon or some other suitable plastic.

FIG. 6 shows still another form of valve member attached to the blade member 312, this valve member 7 being molded of heavy rubber or neoprene with or Without a metallic spring insert embedded in the rubber. If the side rail 3b is made of metal, the rubber may be either bonded thereto or otherwise attached for instance by rivets -8.

FIG. 7 shows still another embodiment of the invention in which the entire slide assembly including the valve is one piece, for instance, stamped out of a single stainless steel sheet, which sheet provides the strap portions, such as strap 9c, the blades 9a and 9b and the valve member 9v, which is connected to the blade 9b by a round springlike loop 9s.

Referring now to FIGS. 1, 2 and 3, these three figures show a sequence of events occurring during normal operation of the present migratory scraper assembly. In FIG. 1, the scraper body 1 is descending in the direction of the arrow B toward the upset U at the lower end of the sucker rod R against the flow of fluid travelling in the direction of the arrows F. The actuating slide 3 and valve member 2 are in open position so that the fluid is relatively free to travel into the passageway P and upwardly through the slot Is to facilitate fluid flow and permit the assembly to gravitate downwardly. The fluid passes around, under and over, the blades 3a and 3b in the general paths indicated by the arrows F to enter the slot. As the assembly drops, eventually the annular strap portion 30 of the assembly will bottom against the lower upset U (or a fixed-scraper abutment), and the body '1 will settle downwardly on the blades 3a and 3b to assist an upward stroke of the rod to drive the plug valve member 2. into the slot 1c to assume the position shown in FIG. 2. The fluid passageway P through the slot is thus greatly restricted by the valve member 2, thereby increasing the resistance of the scraper to the flow of fluid therepast in the direction of the arrow F, with the result that the whole scraper assembly resembles a piston which is buoyed up by the rising fluid F and forced to migrate upwardly on the sucker rod R, thereby scraping paraflin from the outer surface thereof and the inner surface of the tubing T.

Eventually, the upper strap portion 3d of the slide member 3 will abut the upset U (or another fixed-scraper or rod guide G as shown in FIG. 8 and serving as an abutment) at the upper end of the sucker rod R, FIG. 3, and upon further upward advance by the body 1, the valve member 2 will be dislodged from the slot 10, thereby reopening the slot to bypass the fluid F therethrough and again reduce the buoyancy of the body 1 sufiiciently so that the force of gravity and the motion of the rod will cause it to drop through the rising fluid F. The scraper assembly will continue to drop until it reaches the position shown in FIG. 1, at which time the valve member 2 will be closed again by re-entry into the slot 10.

As is well-known to those skilled in the art, the fluid within the tubing T rotates during the pumping operation, and this has a tendency to rotate the body 1 and the blades 3a and 312 so as to increase their parafiin scraping efficiency by assisting the longitudinal inside and outside edges of the latter to function as paraffin scraping edges, thereby improving the cleaning action of the body both upon the sucker rod R and on the inner surfaces of the tubing T.

The present invention is not to be limited to the exact forms shown in the drawing, for obviously changes may be made therein within the scope of the following claims.

What I claim is:

1. In oil well equipment, a migratory parafiin scraper for scraping both the surface of a length of sucker rod between abutments spaced therealong and the walls of surrounding tubing, comprising:

(a) a body of diameter less than the inside diameter of the tubing and having a bore therethrough sized to freely receive said length of rod, and the body having a slot through its side wall, the spacing between the sides of the slot approximating the diameter of said length of rod and the slot communicating with the bore along the full length of the body;

(b) a sliding assembly including opposed blades which are substantially longer than the body and lie against the sides of the slot in mutually spaced relationship to leave a passageway therebetween, and said assembly including means joining each of the blades and extending around the rod to prevent the blades from leaving the slot; and

(c) passageway restriction means supported by and extending between the blades and so located that when said assembly is longitudinally displaced in one direction with respect to the body the restriction means is inside the slot and when the assembly is longitudinally displaced in the opposite direction with respect to the body the restriction means is outside of the slot.

2. In a migratory scraper as set forth in claim 1, said rod and tubing being vertical, and said restriction means being so located between the blades that it is inside the slot when the sliding assembly is displaced upwardly with respect to the body and outside the slot when the assembly is displaced downwardly with respect to the body.

3. In a migratory scraper as set forth in claim 2, said restriction means comprising a spring valve member extending across said passageway under normal pressure differential conditions, but yieldable to open the passageway under extreme pressure differential conditions.

4. In a migratory scraper as set forth in claim 1, said sliding assembly comprising opposed blades having their ends extending beyond the opposite ends of said body, and said joining means including a C-shaped strap at each end of the assembly and each extending loosely around the rod and having its ends joined with the ends of the blades to prevent the latter from being longitudinally withdrawn from the slot, the rod being insertable into the sliding assembly through the passageway and the open ends of the C-shaped straps.

5. In a migratory scraper as set forth in claim 4, said sliding assembly comprising a one-piece sheet metal member.

6. In a migratory scraper as set forth in claim 4, said abutments comprising upsets at the ends of the sucker rod, and the outwardly facing ends of said C-shaped straps being flared to contact said upsets without gouging them.

7. In a migratory scraper as set forth in claim 4, said restriction means comprising a leaf of spring-like material attached at one end to one of said blades and extending across the passageway into yieldable contact with the other blade, thereby normally blocking said passageway in the absence of a pressure differential suflicient to flex the leaf out of contact with said other blade.

8. In a migratory scraper as set forth in claim 7, said leaf comprising a steel spring, and said sliding assembly including the spring being coated with a corrosion resistant material.

9. In a migratory scraper as set forth in claim 7, said leaf comprising elastomeric material.

10. In a migratory scraper as set forth in claim 7, said sliding assembly, including said blades and said straps and said leaf, all comprising a one-piece sheet material member.

11. In a migratory scraper as set forth in claim 7, said sliding assembly including said straps, said blade and said leaf all comprising a one-piece molded plastic member, such as nylon.

12. In oil well equipment, a migratory paraflin scraper for scraping both the surface of a length of sucker rod between abutments spaced therealong and the walls of surrounding tubing, comprising:

(a) a cylindrical body molded of resilient rubber-like material and having a diameter less than the inside diameter of the tubing and having a bore therethrough sized to freely receive said length of rod, and the body having a slot through its side wall, the spacing between the sides of the slot approximating the diameter of said length of rod and the slot com- 8 municating with the bore along the full length of respect to the body, the restriction means is outside the body; of the slot. (b) a C-shaped spring steel clip embedded within the 13. In oil equipment the combination with a migratory body and surrounding the bore, the opening in the scraper as set forth in claim 12 for scraping the well clip registering with said slot and said body having 5 tubing and the surface of the sucker rod between said narrow pierced radial punctures extending deeply inabutments, and abutments comprising fixed-type sucker wardly to depths short of said embedded clip, said rod guides mounted near the ends of the sucker rod and punctures being distributed over substantially all of having outside diameters greater than the migratory said body and mutually spaced by distances not exscrapers and less than said tubing whereby the fixed guides ceeding the depths of the punctures; 10 centralize the rod in the tubing and limit its lateral move- (c) a sliding assembl including opposed blades which ment therein from preventing free migration of the scraper.

are substantially longer than the body and lie against the sides of the slot in mutually spaced relationship to References Clted leave a passageway therebetween, and said assembly UNITED S A ES PA NTS including means joining each of the blades and ex- 15 tending around the rod to prevent the blades from ggi g leavmg the i 3,330,359 7/1967 Ward 166-175 (d) passageway restriction means supported by and eX- 3 364 998 1/1968 Sable X tending between the blades and so located that when said assembly is longitudinally displaced in one di- 20 DAVID BROWN Primary Examiner rection with respect to the body the restriction means is inside the slot and when the assembly is lOngi- US, Cl. X.R. tudinally displaced in the opposite direction with 166-476 

